Improvement on soil freeze/thaw discriminant algorithm under complex surface conditions in cold regions

2017 ◽  
Author(s):  
Wenxing Hu ◽  
Linna Chai ◽  
Shaojie Zhao ◽  
Tianjie Zhao ◽  
Zheng Lu
Keyword(s):  
Complex Surface ◽  
Cold Regions ◽  
Surface Conditions ◽  
Freeze Thaw

scholarly journals The Effects of Particle Gradation on Salinized Soil in Arid and Cold Regions

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 236
Author(s):  
Xuebang Huang ◽  
Zizhao Zhang ◽  
Ruihua Hao ◽  
Zezhou Guo
Keyword(s):  
Particle Size ◽  
Soil Samples ◽  
Frost Heaving ◽  
Particle Content ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Salinized Soil ◽  
Size Grading

Particle size grading impacts salt-frost heaving and dissolution collapse events of salinized soil on northwestern China’s arid and cold region highways. However, the influencing mechanisms remain unclear and the impact of varying particle size grading needs further investigation. Hence, this study focused on these effects and the number of freeze–thaw cycles on the characteristic changes in highway salinized soil in arid and cold regions. Three soil columns with different gradations were prepared to explore the gradation and the number of freeze–thaw cycle affects on salinized soil’s salt-frost heaving and dissolution collapse characteristics. The multi-functional physical simulation platform conducted multiple freeze–thaw cyclic tests in the laboratory. Test results confirmed significant and conclusive effects of gradation and the number of freeze–thaw cycles on salinized soil’s salt-frost heaving and dissolution collapse behaviors. Poorly graded salinized soil with high coarse particle content caused repeated freeze and thaw engineering hazards, significantly affecting salinized soil’s displacement and deformation behaviors during freezing. Contrarily, an increased range of fine particles more easily involved the characteristics of salinized soil during thawing. Therefore, the fourth freeze–thaw cycle was a crucial time node. After four freeze–thaw cycles, the displacement and deformation of original salinized soil and B-grade salinized soil samples (poorly graded with high fine particle content) tended to be stable. In contrast, the displacement and deformation of A-grade salinized soil samples (poorly graded with high coarse particle content) increased the growth rate. The present research results contribute to in-depth knowledge of the effects of gradation and freeze–thaw cycles on the characteristics of salinized soil in northwestern China, providing excellent referenced data support for the prevention and control of highway salinized soil failures and other engineering projects in arid and cold regions of northwest China.

scholarly journals Geomechanical and Acoustic Properties of Intact Granite Subjected to Freeze–Thaw Cycles during Water-Ice Phase Transformation in Beizhan’s Open Pit Mine Slope, Xinjiang, China

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2309 ◽  
Author(s):  
Yu Wang ◽  
Wenkai Feng ◽  
Huajian Wang ◽  
Jianqiang Han ◽  
Changhong Li
Keyword(s):  
Energy Balance ◽  
Fatigue Damage ◽  
Frequency Band ◽  
Open Pit Mine ◽  
Acoustic Properties ◽  
Open Pit ◽  
Cold Regions ◽  
Detection Techniques ◽  
Freeze Thaw ◽  
Energy Balance Approach

The deterioration of rock geomechanical behaviors subjected to freeze–thaw (F–T) action is a determining factor for rock engineering and rock structures in cold regions. In this work, taking six groups of granite obtained from an open pit mine as the research object, F–T cycle treatment, in-situ AE (acoustic emission) monitoring and ultrasonic detection techniques were performed to experimentally reveal the effects of F–T fatigue damage on the mechanical and acoustic properties of granite. The results indicate that the F–T action impacts the rock’s mesoscopic structure, deformation, strength, P and S-wave velocities, AE pattern and energy release. The accumulated AE counts and accumulated AE energy show a decreasing trend as the F–T cycle increases. The frequency spectrum revealed that the width of the low frequency band decreases and the high frequency band increases with increasing F–T cycles, indicating that there is an increase in large-scale cracks for a sample with high F–T treatment. In addition, energy balance analysis further illustrates the energy dissipation and release mechanism. The energy proportion used to drive the crack propagation is relatively small with high F–T treatment, and the final released energy becomes the minimum. The energy evolution characteristics analyzed by the energy balance approach is in good agreement with AE results. It is suggested that the F–T fatigue damage influences the rock energy storage and release characteristics and the instability of rock in the cold regions.

Mechanical and electrical properties of coarse-grained soil affected by cyclic freeze-thaw in high cold regions

2020 ◽  
Vol 27 (3) ◽  
pp. 853-866
Author(s):  
Yong-long Qu ◽  
Wan-kui Ni ◽  
Fu-jun Niu ◽  
Yan-hu Mu ◽  
Guo-liang Chen ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Coarse Grained ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Mechanical And Electrical Properties ◽  
Coarse Grained Soil

scholarly journals Research on the Pore Evolution of Sandstone in Cold Regions under Freeze-Thaw Weathering Cycles Based on NMR

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zheng Pan ◽  
Keping Zhou ◽  
Rugao Gao ◽  
Zhen Jiang ◽  
Chun Yang ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Pore Structure ◽  
Western China ◽  
Cold Regions ◽  
Abrupt Decrease ◽  
Evolution Law ◽  
Red Sandstone ◽  
Freeze Thaw ◽  
Evolution Characteristics ◽  
Pore Evolution

The evolution of the rock pore structure is an important factor influencing rock mechanical properties in cold regions. To study the mesoscopic evolution law of the rock pore structure under freeze-thaw weathering cycles, a freeze-thaw weathering cycle experiment was performed on red sandstone from the cold region of western China with temperatures ranging from -20°C to +20°C. The porosity, T2 spectral distribution, and magnetic resonance imaging (MRI) characteristics of the red sandstone after 0, 20, 40, 60, 80, 100, and 120 freeze-thaw weathering cycles were measured by the nondestructive detection technique nuclear magnetic resonance (NMR). The results show that the porosity of sandstone decreases first and then increases with the increase of the freeze-thaw weathering cycles and reaches the minimum at 60 of freeze-thaw weathering cycles. The evolution characteristics of porosity can be divided into three stages, namely, the abrupt decrease in porosity, the slow decrease in porosity, and the steady increase in porosity. The evolution characteristics of the T2 spectrum distribution, movable fluid porosity (MFP), and MRI images in response to the freeze-thaw weathering process are positively correlated with the porosity. Analysis of the experimental data reveals that the decrease in the porosity of the red sandstone is mainly governed by mesopores, which is related to the water swelling phenomenon of montmorillonite. Hence, the pore connectivity decreases. As the number of freeze-thaw cycles increases, the effect of the hydrophysical reaction on the porosity gradually disappears, and the frost heaving effect caused by the water-ice phase transition gradually dominates the pore evolution law of red sandstone.

2D anisotropic multicomponent Gaussian-beam migration under complex surface conditions

Geophysics ◽  
2020 ◽  
Vol 85 (2) ◽  
pp. S89-S102 ◽  
Author(s):  
Jianguang Han ◽  
Qingtian Lü ◽  
Bingluo Gu ◽  
Jiayong Yan ◽  
Hao Zhang
Keyword(s):  
Gaussian Beam ◽  
Complex Surface ◽  
Dynamic Features ◽  
Surface Conditions ◽  
Depth Migration ◽  
Surface Areas ◽  
Local Plane ◽  
Gaussian Beam Migration ◽  
Wave Migration ◽  
Irregular Topography

Elastic-wave migration in anisotropic media is a vital challenge, particularly for areas with irregular topography. Gaussian-beam migration (GBM) is an accurate and flexible depth migration technique, which is adaptable for imaging complex surface areas. It retains the dynamic features of the wavefield and overcomes the multivalued traveltimes and caustic problems of Kirchhoff migration. We have extended the GBM method to work for 2D anisotropic multicomponent migration under complex surface conditions. We use Gaussian beams to calculate the wavefield from irregular topography, and we use two schemes to derive the down-continued recorded wavefields. One is based on the local slant stack as in classic GBM, in which the PP- and PS-wave seismic records within the local region are directly decomposed into local plane-wave components from irregular topography. The other scheme does not perform the local slant stack. The Green’s function is calculated with a Gaussian beam summation emitted from the receiver point at the irregular surface. Using the crosscorrelation imaging condition and combining with the 2D anisotropic ray-tracing algorithm, we develop two 2D anisotropic multicomponent Gaussian-beam prestack depth migration (GB-PSDM) methods, i.e., using the slant stack and nonslant stack, for irregular topography. Numerical tests demonstrate that our anisotropic multicomponent GB-PSDM can accurately image subsurface structures under complex topography conditions.

scholarly journals Characteristics of Unloading Creep of Tuffaceous Sandstone in East Tianshan Tunnel under Freeze-Thaw Cycles

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Zhijun Zhou ◽  
Haochen Zhan ◽  
Jiangyang Hu ◽  
Chenning Ren
Keyword(s):  
Creep Rate ◽  
Surrounding Rock ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Rock Samples ◽  
Thaw Cycle ◽  
Short Period ◽  
Macro Scale ◽  
Freeze Thaw Cycle ◽  
East Tianshan

The physicomechanical properties of tunnel surrounding rock are influenced by many factors such as the external environment and freeze-thaw cycles, especially in engineering in high cold regions. To understand the characteristics of freeze-thaw cycles on the creep properties of rocks in high cold regions, a freeze-thaw test, SEM test, triaxial compression test, and triaxial unloading creep test were carried out for tuffaceous sandstone in the G575 East Tianshan Tunnel in Hami, Xinjiang. The results show the following: (1) the freeze-thaw cycle reduces the degree of cementation of mineral particles in a microcosm, manifested on a macro scale by the scaling mode and crack propagation mode; (2) the effect of freeze-thaw cycles reduces the compressive strength and shear strength of rock samples (i.e., ductility enhancement); (3) for tuffaceous sandstone, the unloading process and freeze-thaw cycle each lead to improved creep deformation in rock samples, and radial deformation is more sensitive to rock deformation and failure; and (4) the creep rate of surrounding rock can be reduced by confining pressure. The peak creep rate increased with freeze-thaw time, as did the overall creep rate. Attention should be paid to deformation within a short period, and necessary supporting and protection measures should be taken to reduce creep.

Influence of Silane Treatment on the Freeze-Thaw Resistance of Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 565-568 ◽  
Author(s):  
Xiao Jian Gao ◽  
Hong Wei Deng ◽  
Ying Zi Yang
Keyword(s):  
Surface Treatment ◽  
Water Adsorption ◽  
Concrete Structures ◽  
Air Entrainment ◽  
Concrete Surface ◽  
Silane Treatment ◽  
Cold Regions ◽  
Bonding Force ◽  
Freeze Thaw ◽  
Surface Impregnation

The influences of silane impregnation on water adsorption, bonding force between ice and concrete surface and resistance to freeze-thaw of concretes were studied. Two strength grades (C30 and C50) and the air entrainment were considered for concrete preparation. The results show that surface impregnation with silane reduces the final water adsorption of concrete by more than 90% when compared with the untreated specimen. The silane treatment significantly decreases the bonding force between ice and concrete surface. The resistance to freeze-thaw of both new and old concretes can be improved by the silane treatment. Therefore, the surface treatment with silane is suggested as an effective method to improve the durability of concrete structures in cold regions.

Weathering in cold regions: some thoughts and perspectives

2002 ◽  
Vol 26 (4) ◽  
pp. 577-603 ◽  
Author(s):  
Kevin Hall ◽  
Colin E. Thorn ◽  
Norikazu Matsuoka ◽  
Angelique Prick
Keyword(s):  
Arid Regions ◽  
Chemical Weathering ◽  
Current Theory ◽  
Chemical Processes ◽  
Frame Of Reference ◽  
Cold Environment ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Cold Environments ◽  
Palaeoenvironmental Reconstructions

Weathering in cold regions has primarily focused on the notion of ‘cold’, such that process and landform theory have generally used this both as the developmental criterion and as the outcome of palaeoenvironmental reconstructions based on landforms or sediments. As a result of this approach, the process focus in terms of weathering has been that mechanical processes predominate, with freeze-thaw weathering as the prime agent, and that chemical processes are temperature-inhibited, often to the point of nonoccurrence. Here a reconsideration of the whole conceptual framework of weathering in cold environments is undertaken. It is shown that, contrary to popular presentations, weathering, including chemical weathering, is not temperature-limited but rather is limited by moisture availability. Indeed, summer, and oft-times even winter, rock temperatures are more than adequate to support mechanical and chemical weathering if water is present. Where water is available it is clearly shown that chemical weathering can be a major component of the weathering regime. The argument is made that there is no zonality to cold environment weathering as none of the processes or process associations are unique to cold regions; indeed, many cold regions show similar weathering assemblages to those in hot arid regions. Process-form relationships are also questioned. The assumption of angularity with weathering in cold regions is questioned, all the more so as hot arid studies identify exactly the same angularity of debris form. Further, that all forms have to be angular is shown by field examples to be no more than an artefact of original unquestioning and oft-repeated assumptions, now over a century or more old. The argument is made that there is a strong need for the reconsideration of the nature of weathering in cold environments, that current theory should be questioned and challenged, and field observation undertaken within this revised frame of reference.

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